Here at Fairvale Observatory, most of the exciting deep sky objects associated with the transit of the Milky Way during winter have disappeared over the western horizon by early spring. Notwithstanding, a brief period of decent conditions at the very end of March provided a late window of opportunity to image a core area of our galaxy, which being viewed above Oirion at a higher declination in the constellation of Gemini, helped to extend the limited imaging time available. Frankly after such a terrible period of weather since last November, I was desperate to get one last image from this rich part of the night sky and try out my new Chroma narrowband filters again, which thankfully worked out well after imaging IC443 the Jellyfish Nebula over four nights, despite there being less than two hours of suitable viewing and darkness each night.
The remnant of a supernova that occurred between 3,000 and 33,000 years ago, located in the Gemini constellation the Jellyfish Nebula is some 5,000 light years from Earth. With a diameter of 70 light-years, the angular view of the nebula is some 50 arcminutes or nearly twice the size of a full moon. Overall the nebula consists of at least three distinct shells reflecting the complex nature of this Type-II supernova, which is interacting with the surrounding area of molecular clouds.
Red box indicates location and orientation of image
Acknowledging the limited time available – compounded by lingering cloud each night – I chose to image The Jellyfish in narrowband bicolour, hoping to collect some SII photons on another day to add to the Ha & OIII. At the end I also added some short LRGB subs to improve the final star colours and during processing used Ha as a false luminance layer to help bring out the complex structure of the nebula further. The image has been deliberately framed by the adjacent large stars Propus (bottom) and Tejat (top), which caused plenty of problems during processing but in my opinion form an essential component when imaging this object. Whilst IC443 is undoubtedly the main act, it is set off well by the large adjacent area of detailed nebulosity and the smaller reflection nebula IC444 to the right which is easy to overlook. Despite many issues I am very pleased with the final image that beautifully shows off this spectacular DSO and the surrounding region in all its glory, which seems all the better being something of a last chance opportunity that I thought I’d missed for this season.
IMAGING DETAILS
Object
IC443 Jellyfish Nebula & IC444
Constellation
Gemini
Distance
5,000 light-years
Size
50 arc minutes ~70 light years
Apparent Magnitude
+12
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 2.65o x 2.0o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix
The history of astrophotography will record a period of rapid innovation during the past decade, amongst which one of the stand-out developments has been that of the CMOS sensor based camera, notably the ZWO ASI1600MM-Cool (see below). Just look at any astrophotography website such as Astrobin and it won’t take long to find an image taken with this camera such is its popularity. It is this very camera that I was fortunate to purchase in December 2016 shortly after its release and has been the core of my astrophotography set-up ever since.
I have generally been very happy with the results achieved with the ZWO camera, although an issue sometimes occurs when imaging large stars, so called ‘star bloating’. There are a number of theories discussed ad nauseam online why this might occur, of which microlensing and / or diffraction seems most likely and probably relates to either – the sensor, sensor cover or filters. Since beginning with the ZWO camera I’ve used their excellent matching EFW with LRGB and 7nm narrowband filters. Notwithstanding, the filters are considered to be somewhat ‘low end’ by the aficionados of such things and after living with the ZWO filters for some time, at considerable cost I recently decided to upgrade to a set of Chroma 31mm filters – LRGB + 3nm narrowband. Together with Astrodon, Chroma filters are generally considered to be the best and my expectations were therefore high.
Being unmounted I’d previously found the ZWO filters tricky to install using the small screws and fibre washers supplied. At 3mm Chroma are physically 1mm thicker than ZWO filters and also need to be fitted in a specific direction, which is ‘letters up’ or with top of the ID letters on the side of the filter facing towards the sensor; this is disputed by the manufacturer but there’s substantial first-hand experience online that suggests otherwise. With these issues in mind I sought out bespoke filter masks and longer M2 6mm screws to hold the thicker filters firmly in place. The 3D printed masks from Buckeyestargazer in the USA did a great job securing the filters and are better than those from ZWO – the internal edge of the mask forms an L-shaped ledge into which the filter fits snuggly. Ready to go, I then had to wait nearly 4-months before the clouds parted to try out these expensive pieces of glass and then it was a full moon – I often wonder if astrophotography is a good hobby to choose in the United Kingdom but it’s too late now?
Chroma filters secured with Buckeyestargazer masks and ready to go
Given the presence of the moon it therefore had to be suitable narrowband target and after three years since I’d last imaged this object it was an opportunity to have another go at NGC 2244 AKA the Rosette Nebula, though being late February there was limited time each night before the object sunk low behind trees on the western horizon; coincidentally the ZWO ASI1600MM-Cool First Light in early 2017 was also the Rosette. Before starting serious imaging I first tried some test shots to make sure everything worked OK and immediately discovered that the change from 7nm to 3nm had a significant impact on light gathering, thus requiring greater exposure times of an unprecedented 10 minutes. Not surprisingly this was also apparent when taking flats which increased exposure time of up to x10 longer in duration compared to the ZWO filters; conversely preliminary but limited tests on the broadband filters seem to indicate greater transparency and thus shorter exposures, time will tell if this is correct.
So was it all worth it? I’m very pleased with the final image which was processed using the SHO Hubble Palette with PixInsight and Photoshop (see top of the page). There are a number of significant bright stars in and around the Rosette which the Chroma filters have handled well but overall it is the more delicate tone that has been achieved which is most pleasing. Fundamentally the 3nm filters have produced a more subtle quality to the overall image and in particular the nebulosity. In addition, applying Hartmut Bornemann’s excellent colour calibration script AutoColor for the first time (see Visible Dark’s video tutorial here) has resulted in a soft but exciting colour palette.
Subsequently I have focussed on the inner region of the nebula which contains the so-called ‘Carnival of Animals’ (see above), which has been cropped and reprocessed individually to show-off the ‘animals’ or Bok globules – named after the Dutch-American astronomer Bart Bok, who in 1947 proposed that these dark nebula indicated clouds of dust undergoing gravitational collapse as part of the process of new star formation, which has since been confirmed. In conclusion I’d therefore say that despite the obstacles, issues and long wait, on the evidence so far the addition of the Chroma filters to my set-up has been very successful – transformative in fact. Now I wonder if they make something that removes the clouds?
IMAGING DETAILS
Object
NGC 2244 + 2337 + 2238 + 2239 + 2246 AKA the Rosette Nebula
Constellation
Monoceros
Distance
5,200 light-years
Size
65 light-years
Apparent Magnitude
9
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 2.65o x 2.0o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix
After starting astronomy in 2014, Watch This Space (Man) was launched shortly thereafter as a personal record of my then nascent astronomy journey. Apart from the main blog about my progress or otherwise, links to other astrophotographers, astronomy tools, astronomy weather, scientific papers etc. can also be found on this website; I was suprised to see that to-date 152 items have been published on this site.
I always like to hear from others – comments, questions, help or just to say hello – and can be contacted via: graham.s.roberts@gmail.com or just leave a comment at the end of any item if you prefer.
Vistor map 2020: In this most difficult of years for everyone, it’s especially heartening to see so much interest from all corner’s of the world and hope to see you and others again in 2021 – Clear Skies!
REFLECTIONS is a review of my astronomy and astrophotography during the past year, together with some thoughts on possible future developments.
2020 Overview, Images & Goals for 2021
For the world 2020 was a year like no other. Notwithstanding the obvious problems and dire consequences of Covid-19 for everyone, there have been surprising benefits for astronomy. Although I am retired, under lockdown there was even more time available for hobbies. Furthermore, as I live close to Gatwick and Heathrow airports + underneath numerous high altitude long-haul overflight paths, a massive reduction in air travel resulted in a very obvious improvement in seeing conditions, which was confirmed by guiding results. Located in a Bortle 5 to 6 area I ordinarily achieve at best average RMS error guiding of 0.90” to 1.50”/pixel, guiding improved markedly during lockdown to between 0.50” to 0.75”/ pixel. Of course such seeing conditions also resulted in better quality imaging itself and on a number of occasions I was able to achieve integration times of 10-hours or much more over a number of nights. The result was better images but less of them and inevitably, a lot more cloud throughout the rest of the year!
Having previously got to grips with plate solving, using the new CdC planning function I intended to develop the use of mosaics this year. However, such is the weather in the UK (see above) that it’s obvious to me that creating mosaics is probably not the best use of what imaging time we get. Undeterred, during January I planned and shot a 15x panel mosaic of Barnard’s Loop in Ha-wavelength. Unfortunately the unpredictable occurrence of patchy cloud invalidated some of the panels, though I was finally able to compile a 7x panel mosaic of the upper easterly section of Barnard’s Loop – see below. Notwithstanding, there were lessons learned: (i) restrict mosaics to one or two panels and / or (ii) where wider view images are required use a wide FOV set-up rather than a large mosaic.
Most of my other objectives for 2020 turned out to be pipedreams e.g. a new observatory or perhaps a larger telescope or dual rig. Despite this there were important developments on other fronts.
After eventually coming to the conclusion that mosaics were probably an unwise way to go considering UK conditions, it became clear that a suitable high-quality camera lens might produce similar coverage with less imaging time and hassle. Thus also inspired by the images of others on the SGL Forum using such equipment, I set out to build a new rig based around the excellent Samyang 135 f2 lens. This project remains work-in-progress but so far using the lens with a bespoke 3D printed rig and micro focuser made by Astrokraken and a modded DSLR, it’s apparent that this lens produces excellent widefield images in a relatively short time.
Initial Samyang 135 f2 set-up with modded DSLR
With the time and ‘opportunity’ afforded by lockdown throughout most of the year, I finally decided to do something about improving my processing, namely learning PixInsight. Unfortunately the rumours were correct – it is a steep learning curve and altogether a less than user friendly software. However, after many weeks of toil and expletives I’m pleased to say I can now process an entire image with PixInsight, the impact of which has been nothing less than profound. However, whilst PixInsight is an excellent processing facility, I’ve come to the conclusion that it is often best used together with other process software where appropriate for specific tasks:
Deep Sky Stacker for calibration, alignment and stacking; the equivalent PixInsight process is just too complicated and time consuming;
Photoshop can be very helpful finessing colours and stretching (Levels & Curves);
Starnet++ is useful for creating starless images, which then help to get the best from processing nebula separately before re-combining with the stars;
Topaz AI Denoise has been very effective and easy to use for noise reduction and sharpening at any point during the workflow.
This combination for processing has turned out to be something of a game changer and almost certainly was the most important astrophotography development of the year for me, which augurs well for 2021 and beyond.
Favourite Images
Continuing with the theme of less is more, I imaged just 13 objects this year – of which three were experimental & three with a DSLR – but still with a total integration time of 80 hours (2019 17 objects & 65 hours, 2018: 25 objects & 43 hours). Having worked through many of the astronomer’s favourites by now, images in 2020 consisted of: a new approach to old favourites, difficult / small objects for my equipment e.g. galaxies or less popular and widefield targets.
I’m pleased to say that most of these images turned out well and it’s difficult to choose a favourite. The so-called ‘favourites’ below therefore represent those images from this year that portray an important development in my astrophotography journey. More detailed reviews of these and all other images from 2020 can be found in specific articles that can be accessed using the links found below or via the Blog Index, located under the dropdown menu ABOUT.
Heart Nebula: Although imaged in 2018, this version has been re-processed using mainly PixInsight, thus transforming the original SHO Hubble Palette image from something rather dull to one with warm, vibrant colours, as well as much great detail – demonstrating the significant impact of my new PixInsight based processing abilities.
LBN 325: Numerous emission nebulae populate this small part of a very extensiveHII-Region, which forms an exciting LRGB image. Processing was complex and difficult, in order to bring out exciting features that abound in this spectacular but less popular area of the Cygnus constellation. Integration time of 10-hours was obtained over three nights and is my first LRGB image processed using PixInsight.
M63 Sunflower Galaxy: At 12.6’ x 7.2’and apparent magnitude of +9.3,this small flocculent galaxy in the Canes Venatici constellation is a challenge for my equipment. However, with 8 hours 20 minutes exposure over three nights in April and careful processing, the all-important detail within the galactic disc is clear. Topaz Denoise AI and Gigapixel software played an important role in maintaining the colour and delicate detail in this +50% cropped image.
Taken from last year’s REFLECTIONS 2019:
“Although you never know, I don’t see any major breakthroughs in the coming year”. Just goes to show what I know, fewer but better images were obtained in 2020:
RECORD CARD 2020
Goal
Specifics / Results
Outcome
Improve image capture
Further Improvements in overall quality + much longer integration times + better guiding accuracy = less but better images.
MUCH BETTER
Better processing
Using PixInsight software combined with Photoshop, Starnet++ and Topaz Denoise AI has led to major processing improvements and much better final images.
MUCH MUCH BETTER
Widefield Imaging
Initial results from new imaging rig based around Samyang 135 f2 lens were very promising but there’s more to do.
BETTER
My main objectives for 2020 were largely fulfilled (see above), so what about 2021?
Imaging: Other than maintaining the aforesaid improvements achieved over the past two years – guiding & longer integration times – two items that still need to be addressed are: (i) upgrade filters to remove star bloating and all round better images, (ii) improved focussing.
Widefield: Complete Samyang-rig build and switch from DSLR to CMOS mono camera.
Consolidate processing improvements: Whilst the move to PixInsight and other software was very successful in 2020, I’m still only scratching the surface of what’s possible.
Upgrade mono camera – there’s a new generation of colour CMOS cameras starting to appear, hopefully soon to be followed by their mono equivalents !
Hardly a year I and the rest of the world will want to remember, though more than ever astrophotography played a big role in providing relief from the trauma going on around us all.
The major increase of integration times achieved and the use of PixInsight has proved transformative for my astrophotography and will justify returning to reimage some old favourites in future years. I had often thought about upgrading my OTA to something bigger but given the lack of a permanent observatory here at Fairvale Observatory, combined with long periods of bad / cloudy weather, the penny finally dropped and I now have high hopes for the little wonder that is the Samyang 135 f2 lens when I complete its set-up in 2021.
Looking back I have to be happy with my astrophotography in 2020 but more importantly, look forwards to an even better year which holds great promise building on the positive developments of the past 24-months. Moreover, I hope for the sake of everyone that we will be able to deal with Covid-19 soon and return to something of a normal life once again. These are big ambitions and I hope that WTSM’s Reflections 2021 will record such success.
Watch this space!
ASTROPHOTOGRAPHY INDEX OF 2020
To access each blog, click on the title required below highlighted in RED:
An astrophotography image is clearly the sum of its parts, which can broadly be defined as: Equipment – Image Capture – Processing. Much attention and money is given to the first two items but it’s easy to overlook the importance of processing, I should know I’ve done it for years! With time on my hands this year during Covid-19 & lockdown, I have at last turned my attention to this most critical of items to very good effect. Hitherto I’ve used Deep Sky Stacker (DSS) for calibration & stacking, before moving to Photoshop for all other processing, which has usually produced satisfactory results. However, I’ve often thought more might be obtained from the data by using more powerful software combined with an improvement of my overall skills.
On taking up astrophotography it’s a shock when first looking at the camera’s data, which will usually produce a dark almost featureless image, represented by a very narrow, steep image histogram – a graphical representation of the tone and light collected by the exposures. This is because most of the image of the night sky will of course be dark, with precious few photons arriving from distant objects being photographed contained only within the said narrow histogram – the trick is to tease them out during processing in the so-called digital darkroom, thereby revealing the image within.
In the right hands Photoshop is an excellent tool for post processing but it’s no coincidence that most accomplished astrophotographers are using PixInsight(PI), for good reason: it is dedicated to astrophotography, is very powerful, whilst at the same time being very flexible. Unfortunately the learning curve for PixInsight is steep but from my recent experience very much worth the effort. Metaphorically speaking, I’m in the foothills of using PixInsight but now with sufficient knowledge to process images from start to finish, I have already successfully tackled complex LRGB images LBN 325 and NGC 6194. Subsequently I’ve turned my attention to re-processing old narrowband data, which first time round produced unsatisfactory results using Photoshop; this being as much the user as anything else.
Whilst PixInsight was the principal software for this re-processing, it was used in conjunction with Photoshop to achieve certain affects and other newly acquired dedicated software for specific tasks: Starnet++ to produce starless images and Topaz Denoise AIfor noise reduction and sharpening. Using the HST palette in all cases, the workflow (see table at the end) was adapted for each image depending on the characteristics of the object. Before (top) and after (below) images are shown beneath, together with links to the original blogs for more background and imaging information.
NGC 281 Pacman Nebula, August 2019: Whilst the initial HaOO bicolour image looked good I struggled to do the same with the SHO version. However, the transformation after re-processing with PI is, as they say – a whole new ballgame. Vibrant colours have emerged from the previous somewhat gloomy image, together with detailed internal structures. Although somewhat artistic in character, I particularly like the starless version which is shown at the top of the page.
IC 1805 Heart Nebula, August 2018: Like Pacman the original bicolour processing was also successful but SHO much less so. Re-processing has brought out warm colours and details around the inner edge of the heart-shaped nebulosity but it is the striking blue inner region which highlights Melotte-15 at the centre that steals the show. Here fierce stellar forces associated with superhot, young open star clusters, model the adjacent dust clouds into features analogous to those of the Eagle Nebula’s Pillars of Creation.
NGC 2244 Rosette Nebula, February 2018: The Rosette was the most difficult data to re-process and therefore turned out to be the most satisfying. Similar to the Heart Nebula, the rose-like dark nebulous outer region and bright inner edge frames the dramatic, somewhat translucent pale blue inner area. Therein billowing, cloud-like blue nebulosity shows off various internal features, which include an open star cluster at the centre and the so-called Carnival of Animals marching across the lower right quadrant. Altogether new processing has transformed this image into something rather special.
NGC 7000 North America Nebula, August 2017: Although very happy with the original SHO image processed using Photoshop, the revised version is not so much better but different. Use of the SCNR function and subsequent PI and Photoshop colour adjustments have introduced greater detail overall, as well as produced more delicate colours, especially the diaphanous blue nebulosity around the ‘Gulf of Mexico’
NGC 1499 California Nebula, October 2017: In this case re-processing has brought out greater structure throughout the nebula and, to a lesser degree, improved the overall colour. However, the nature of the object, limited integration time and relative lack of what is faint OIII and SII data has probably limited the final impact.
Frankly I found PixInsight a complete pain to understand and use initially, however, with the help of online videos, tutorials and the recently published excellent Mastering PixInsight book, I believe the results more than justify the effort and speak for themselves; overall I’m very pleased with the outcome, which far exceeds my expectations. Notwithstanding, going forwards I can’t see PixInsight being my only processing software (though it could be) but it almost certainly will now become my main choice for post processing, where necessary supplemented by Photoshop and other packages dedicated to specific tasks. It’s a case of using the right tool for the job and the wider combination outlined provides much more flexibility, as well as producing excellent results. All I need now are clear skies!
OUTLINE HST NARROWBAND WORKFLOW*
ACTION
COMMENT
Alignment & Stacking
Deep Sky Stacker
NON-LINEAR PRE-PROCESSING
Dynamic Crop
All stacks
Dynamic Background Extraction (DBE)
Gradient removal
RGB Combination
SHO Hubble palette
Linear Fit
Background Neutralisation
Colour Calibration-1
Deconvolution (sometimes)
Not used here but can be if necessary
Noise Reduction
Use ACDNR or Topaz DeNoise AI
Histogram Transformation
Non-linear stretch
LINEAR PROCESSING
Curves Transformation (CT)
Preliminary to bring out colours but not too strong
Colour Calibration-2
SCNR
Remove Green Hue
Magenta star adjustment
If present + use PixelMath script
Starnet++
Separate Nebula & Stars
(a) Curves Transformation & / or (b) Colour Saturation
Colour punch Apply Range Mask to accentuate specific areas
Photoshop – selective colours
Further specific colour adjustment
Re-combine starless & stars images
PixelMath script + experiment with proportions
Final adjustments where necessary
DBE + CT + ACDNR or DeNoise AI + Linear / Curves adjustment
In September I returned to the Cygnus constellation, popular for The North America and Veil Nebula at this time of the year but elsewhere often overlooked by astrophotographers. In particular the vast HII-region that is located around the Deneb-Sadr area which contains an abundance of exciting imaging opportunities, this time my target was LBN325 which contains numerous Ha emission nebulae, a dark nebula and a supernova remnant. To capture these features at their best, I chose to shoot, process and then combine separate HaOO narrowband and RGB images for the first time.
Integrating RGB data for better star colours and narrowband data for nebulosity turned out to be tricky but by removing the stars from the narrowband nebulosity and then processing the starless image before combining with RGB image manually eventually worked out well (see top-of-the-page image). However, the narrowband and broadband data had respectively been taken either side of the Meridian without plate solving and unfortunately my manual alignment was on this occasion poor. However, with careful cropping I was eventually able to able to align and combine each of the images, though at the cost of losing 25% of the overall field-of-view which did not overlap; see full size Ha-image below with interesting features along left and right edges which had to be cropped out to align the final narrowband and broadband images.
In addition to LBN325 there are a large number of other notable features (see Image Details table at the end & Nico Carver’s annotated image below – green outline delineates areas of my image). In addition to the many Ha emission nebulae, the most noteworthy are the dark nebula Barnard 345 and a large section of the Supernova Remnant G082.2+53. Some 100 light-years in total diameter, this OIII-rich feature is unfortunately too faint to be picked out in my image, which would require significantly more OIII data to be seen. Looking further afield of the image the continuing richness of the adjoining area cannot be overstated, which is beautifully seen in Nico Carver’s accompanying image (Northwestern Cygnus by Nico Carver is licensed under a CC BY-SA 4.0 License) – an 8-pannel 46-hour mosaic! I can only dream of such work but certainly hope to return to this area again when possible, in order to enjoy more of the exquisite objects that can be found across this truly exciting area of Cygnus. But for now there’s another story about this image.
For some time I’ve known that I had to improve my processing skills and to this end purchased PixInsight software at the beginning of the year. Very few of the best astrophotographers do not use this processing software but PixInsight has a notoriously steep learning curve and no doubt like many others I gave up after a few days! I can unequivocally say that PixInsight is by far the most user unfriendly software I’ve come across in nearly four decades; there’s no denying it’s abilities but the developers clearly gave very little thought to its users. Nonetheless, spurred on by the need to improve my images and the ‘opportunity’ of more time that Covid-19 has provided us all recently, I returned to PixInsight a number of times over the summer and slowly made progress.
Cropped HaLRGB M101 practice image from scratch – using Pixel Math to add Ha has worked within the galaxy but unfortunately seems to have spread into other areas too!
Using my existing data for M101, I first spent many days working through the calibration and integration process, which can only be described as exhausting! Undeterred and in an effort to speed up matters, I moved on to Batch Processing, which though helpful only partially assists the overall task of pre-processing and inevitably put PixInsight aside again in order to find renewed enthusiasm to continue. From this initial experience I had already come to one conclusion – that I would not be using PixInsight for calibration and integration, continuing for now with Deep Sky Stacker and possibly later switching to either Astro Pixel Processor (APP) or Astro Art, both of which get good user reviews.
From the results of others it’s clear that PixInsight is a route to better images and there is no shortage of online tutorials and books but hitherto I’d not found one that worked well for me. Online tutorials by Light Vortex Astronomy are an excellent learning aid but tricky to work with on screen and Harry’s Astro Shed video tutorials were also helpful but I needed a book on the matter to read, thumb through and casually refer to when needed. Then I got lucky!
It was my good fortune that in May a new text by Rogelio Bernal Andreo (AKA ‘RBA’) Mastering PixInsight became first digitally available and then in September was published as a book. The work is divided into two well thought out and presented volumes:
A comprehensive, easy-to-follow and understand description of how to use PixInsight
A reference guide providing more in-depth information on specific PixInsight processes
The two volumes come as a boxed set, are well bound and illustrated and for the first time (from my point-of-view) form an accessible, easy to use and helpful text on PixInsight. RBA deserves every success with this outstanding book(s) which I believe will transform the otherwise torrid experience of learning PixInsight. Armed with RBA’s Mastering PixInsight, Light VortexAstronomy online tutorials, Harry’s Astro Shed and a other online videos, I’m pleased to say that I am now at last able to use PixInsight for processing and LBN325 is my first image; I should also mention Shawn Nielsen’s excellent Visible Dark YouTube channel, which demonstrates a number of very useful techniques.
As my first attempt to use PixInsight for processing, I’m pleased with the outcome of LBN 325 but realise there’s still much more to learn and, aside from the framing error, it’s clear that even more integration time is needed to get the best of LBN325 and its companions. Going forwards PixInsight and Photoshop both have their respective strengths and weaknesses and judicious use of various techniques from each is probably going to yield the best results. For now, at least, I feel the considerable time put into learning PixInsight is starting to pay off and I’ve finally turned a corner with my processing.
Following a very poor winter period, spring has been nothing less than spectacular and provided many clear nights for astronomy, ironically made all the better by the covid-19 lockdown. With the near absence of road traffic and especially aircraft – Fairvale Observatory is badly affected by flights from nearby Gatwick, Heathrow and Redhill aerodrome – it has resulted in noticeably better seeing, as well as a quieter and more enjoyable environment overall; it’s worth noting that after experimenting with Deep Sky Stacker (DSS), increasing the Kappa-Sigma clipping parameter from 2.0 to 2.50 for the light subs, in all but the worst cases eliminated aircraft tracks in the final stacked image. Resulting from these favourable conditions, I’ve recently been able to image four otherwise difficult targets, amounting to some 40-hours total integration time, literally unprecedented conditions in the +30 years I’ve lived here.
Apart from a brief diversion imaging the Leo Triplet, my attention has otherwise been centered on the constellation of Canes Venatici, AKA the Hunting Dogs. At this time of the year the constellation starts to come into view high overhead from the east at about 10 p.m. and crosses the meridian about three hours later. Located below Ursa Major and above Bootes, the relatively small Canes Venatici hosts five Messier objects, four of which are galaxies and it is these I’ve been drawn to. From earlier test shots I determined that the M94 galaxy was unlikely to be suitable for my equipment but I did obtain and have already described images of first M106 and then M63. Notwithstanding, I had unfinished business with the last of the four galaxies, which I therefore now turned to.
In 2019 I was pleased to acquire my first ever image of the wonderful M51Whirlpool Galaxy and its smaller companion, NGC 5195. However, I noted then that the final LRGB image still needed much more integration time than just 2hr 18min. achieved, plus the addition of Ha-subs and that I hoped to return to the Whirlpool and its neighbour as soon as possible for this purpose.
It was therefore a great pleasure to image M51 over no less than seven nights in March and April this spring, which combined with last year’s data resulted in over 16 hours integration time, substantially longer than any previous image I’ve compiled before. Moreover, the quality of seeing also benefitted SNR and guiding quality, thus achieving RMS errors of at least 0.80 arc seconds or better. I did encounter some plate solving issues and had to resort to manual framing on a few nights but fortunately DSS software dealt with alignment OK and the final image is all I could have hoped for (see above + top-of-the-page cropped). Naturally the interaction of the two galaxies is the signature feature of this image but it is the improvement in general colour, detail and addition of Ha-subs highlighting regions of new star formation, that have been most transformative in portraying these objects in all their glory.
Using my current set-up it seems unlikely that the image would benefit significantly from any further data acquisition but I’d like to think I’ll return another day using a larger telescope and higher resolution with which to capture and enjoy even more detail of all these exciting objects of Canes Venatici. It is said that “it’s an ill wind that blows no good” and I am doubtful we’ll ever have such good conditions here again but for now I was delighted to be able to positively exploit this otherwise difficult time in lockdown.
IMAGING DETAILS
Object
M51 The Whirlpool Galaxy & NGC 5951
Constellation
Canes Venatici
Distance
23 million light-years
Size
11.2’ x 6.9’ 77,000 light-years (M51 only)
Apparent Magnitude
+8.4
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 2.65o x 2.0o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix
You don’t have to be an astronomer to appreciate Van Gogh’s wonderful evocation of the night sky in his 1889 painting Starry Night. He knew a thing or two about sunflowers too and I’ve often stopped by the National Gallery in Trafalgar Square to take a peep at his famous painting of them. However, it was still more than thirty years after completing these paintings that we first learned that such features as galaxies and the rest of the Universe even existed beyond our own Milky Way. Since then our knowledge of the cosmos has expanded considerably and today provides no end of imaging opportunities for the astrophotographer, subject to clear skies!
Having started the galaxy season with M106 and, given the excellent conditions that prevailed throughout much of Spring this year, I chose to return to the same area of the sky again to image M63, AKA the Sunflower Galaxy. M63 has a spiral form but with no apparent central bar and in visible light lacks large scale spiral structure, although two-arm structures are noticeable in near infra-red. Instead the dust lanes are extensively disrupted producing a patchy appearance and is thus classified as a flocculent galaxy – in this case looking something like a sunflower.
As previously discussed, most galaxies are a real challenge for my equipment but an earlier experiment indicated it might just be possible to image M63, the trick would be obtaining sufficient integration time. Fortunately three clear nights approaching a new moon in April provided over 8-hours of good subs, which I’m pleased to say resulted in a decent final image after all. The background sky is less busy than I would wish but there’s nice colour in the stars and also a few very small faint fuzzies on close inspection. Notwithstanding, M63 is clearly the star of the show (no pun intended) with the so-called flocculation clearly evident and numerous random dust lanes criss-crossing the entire galactic disc.
Although in 1924 Edwin Hubble’s recognition that galaxies, such as our own, existed outside the Milky Way, M63 was discovered by Pierre Méchain and catalogued by Charles Messier in 1779, long before Van Gogh’s paintings. He might conceivably have known of its presence therefore but not what it was and would surely be inspired to see and know about the Sunflower Galaxy as we do today.
IMAGING DETAILS
Object
M63, NGC 5055 AKA Sunflower Galaxy
Constellation
Canes Venatici
Distance
29 million light-years
Size
12.6’ x 7.2’
Apparent Magnitude
+9.3
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 2.65o x 2.0o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix
The period between March and May provides an excellent opportunity to see and image objects in and around the constellation of Leo. Located close to the ecliptic, this area of the sky is packed with galaxies and can therefore be seen from most parts of the northern and southern hemispheres. Located to the east of the Leo 1 Group is perhaps the best known of these M65, M66 and NGC 3628, also known as the Leo Triplet.
I last imaged this attractive group of galaxies shortly after changing to a CMOS mono camera in March 2017. Unfortunately on that occasion it was only a test with just 45 minutes integration time at 300-gain, so a more serious attempt to image these three beauties was obviously long overdue. On this occasion imaging over three nights during late March and then finally again in April produced well over 7-hours of integration time.
Whilst the earlier test image showed promise, each of these objects is small and certainly push my equipment it to the limit. However, the benefit of much longer time and imaging at unity settings is self-evident. I’m very pleased with the final LRGB image, which shows good detail and colour for all three galaxies. Furthermore, the advantage of a wider view using the William Optics GT81 and ZWO ASI1600MM-Cool camera combination, has also captured numerous other colorful stars and even smaller galaxies, thereby providing a more interesting background for the main show – the Leo Triplet (see below).
Each of the galaxies that make up the Leo Triplet is tilted at different angles relative to the view from Earth, thereby producing a variety of form and perspective in the image (cropped &adjusted toaccurate orientation @ top-of-the-page). In addition, various distortions of the galactic discs and other effects demonstrate that the three galaxies in the M66 Group have all been affected by gravitational interactions with each other. Seen edge-on, the unbarred spiral galaxy NGC 3628 clearly shows a broad band of dust stretching along its outer edge, thus obscuring young stars within the galaxy’s spiral arms. NGC 3628 seems to be the most affected by the said intergalactic forces which, moreover, has drawn out a tidal tail from the eastern side of the galaxy spanning some 300,000 light years; unfortunately the aforesaid tail is very faint and does not often appear in images – something for another day and a larger telescope!
IMAGING DETAILS
Objects
The Leo Triplet or M66 Group: M65, M66, NGC 628 AKA the Hamburger or Sarah’s Galaxy
Constellation
Leo
Distance
35 million light-years
Size
M65 = 8.71’ x 2.45’ M66 = 9.1’ x 4.2’ NGC 3628 = 15.0’ x 3.6’
Apparent Magnitude
M65 +10.3 M66 +9.97 NGC 3628 +9.4
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 2.65o x 2.0o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix
Having last year discovered that I could see parts of the zenith region of the sky at Fairvale Observatory (North), in particular Ursa Major and adjacent constellations for short periods during the spring galaxy season, it was an obvious location to return to this year. Furthermore, a protracted period of good weather for most of 12-days coinciding with a New Moon provided an unprecedented opportunity to obtain long integration times on a number of smaller galaxies that abound there.
Following the aforementioned discovery, I was pleased to successfully image M101 AKA the Pinwheel Galaxy in 2019. On this occasion I decided to start with M106 in the adjacent Canes Venatici (“the Hunting Dogs”) constellation, an intermediate galaxy thought to have a supermassive black hole at its centre (see location map and image orientation above). Smaller than M101 with a slightly warped disc and viewed obliquely, it is not an easy target with my equipment but the area also teems with other galaxies and colourful stars that make for an attractive composition; it is intriguing that M106 is of similar size and luminosity to the Andromeda Galaxy M31 but is much further away.
Taken over five evenings, the final HaLRGB image integration time of nearly 10 hours is the longest I’ve achieved to-date, producing a pleasing image of M106 with good colours and detail throughout the surrounding area (see image at the top-of-the-page). Moreover, across the wider field-of-view a number of other galaxies can be seen clearly, thereby framing the centrally placed M106 and making for a more dramatic image (see annotated kimage above).
Most of the other galaxies vary in age between 20 to 60 million years old, with the edge-on spiral galaxy NGC 4217 thought to possibly be a companion galaxy of M106, however, it is NGC 4226 that I am most excited by. Close to NGC 4217 and resolved only as a small blurred area with my equipment, nonetheless the light from this galaxy has travelled for 334 million years before reaching my camera. The time it left the galaxy we know as the Carboniferous period, when the major coal measures and rocks of the Yorkshire and the Mendip Hills were laid down, a long time before even dinosaurs roamed the Earth – ancient photons from amongst the furthest distance I’ve ever managed to capture on my sensor!
IMAGING DETAILS
Object
M106 AKA NGC 4258
Constellation
Canes Venatici
Distance
24 million light-years
Size
18.6’ x 7.2’ Diameter 135,000 light-years
Apparent Magnitude
+8.4
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQ-ASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 2.65o x 2.0o Resolution 2.05”/px Max. image size 4,656 x 3,520 px
It seems the start of the year has been jinxed, resulting in something of a mixed bag for my astronomy but thankfully not without some positives. A combination of illness, house decoration and some quite awful weather, really curtailed the possibility of any significant astrophotography projects. Despite these difficulties, in the few moments that were available I have managed to carry out some useful experiments which hopefully lay the foundations for greater things the future – clear skies permitting!
Following the success of my first mosaic in 2019, I decided to undertake something more ambitious over the winter, inevitably returning to Orion – specifically Barnards’s Loop. Unseen with the naked eye, the camera discloses the presence of this large arc of ionized gas that is approximately centered on the Orion Nebula, so large that only a conventional wide field camera lens can usually capture the entire Loop. To obtain a higher quality image using a telescope it’s therefore necessary to create a mosaic. With this in mind and keen to expand – physically and metaphorically – my use of the mosaic technique, Barnard’s Loop seemed a worthy object.
I planned and compiled my previous mosaic of the Heart & Soul Nebula manually but following the recent addition of a mosaic tool to Cartes du Ciel (CdC), which importantly also integrates with my image capture software Astro Photography Tool (APT), this time I was able to plan a 14 (2×7) panel mosaic to image Barnard’s Loop (see accompanying CdC plan above) and the adjacent region. With the ability to vary the overlap and mosaic size up to 10 x 10 panels, once constructed using the CdC mosaic planning the related data is saved to a file, which can then be imported as a series of custom objects into the Point Craft plate solving section of APT; each object is defined by its central RA and DEC co-ordinates. Thereafter, using the plate solving function, the camera and scope are centered one-by-one on each panel for imaging, either manually or by writing a suitable script to automate imaging.
Given the size of the undertaking and difficulties with weather at this time of the year inevitably limiting imaging time, plus the strong Ha-nature of Barnard’s Loop, I chose to confine imaging to only Ha subs, which would pick-out the feature well and thus form a good basis for compiling the final mosaic. The project started well on 3rd January when I was able to complete imaging the three panels covering the central sections of the large upper arm of the arc, unfortunately thereafter it all went downhill – mostly!
As Orion and therefore the Loop moved inexorably westwards, imaging time became increasingly restricted, further compounded by poor weather and when it was clear, poor seeing conditions. Thus acquisition of the remaining panels became more and more difficult, with many of the resulting panels of only poor quality. All-in all I managed to image twelve of the total 17 panels, adding three to the original plan to incorporate the lower ‘tail’ located between Saiph and Rigel. Whilst the said panels covered the entire feature, such was the poor quality of many they could not be used to achieve the final aim of the project – a Ha-image of the entire Barnard’s Loop.
Using Microsoft’s ICE software, the upper section of the Loop came together well but I’ve not been able to incorporate the middle and lower sections which were of low-quality. I’m quite pleased with the general outcome but consider the project has demonstrated that very large mosaics of this scale are an unlikely proposition at Fairvale Observatory given UK weather conditions and lack of a permanent a setup required to maximize imaging opportunities. Notwithstanding, I believe up to four panel mosaics should be OK – we shall see.
Subsequently the weather was very bad and very, very wet, so unable to image I reprocessed NGC 1333 from last year, which at the time had not come out well. I’d previously noticed that for some reason images had been exhibiting poor quality in the corners, where for no obvious reason stars showed trailing in the processed stacks – though not in the original subs. The solution, thankfully discovered via the Deep Sky Stacking Forum, was to change the Stacking Alignment setting from Automatic to Bilinear and bingo, all was well.
NGC 1333 is a colorful reflection nebula located within the dark nebula Rho Ophiuchi, a vast area of gas and dust which is one of the closest star forming regions to the Solar System. In order to evaluate its potential for my equipment I collected just over two hours of LRGB data in January 2019. As previously noted, at the time I was disappointed with the outcome but I now think the revised image processing indicates that with much greater integration time this object could work with more subs – watch this space.
As the bad weather continued throughout most of February there have been very few clear skies but on two such nights I managed brief imaging tests of two other January / February objects which I hope to return to in another year. First of these was another dark nebula Barnard 22, illuminated from behind by the reflection nebula IC 2087. With total LRGB imaging time of just 1hr 24 minutes the processed image was extremely noisy but it was good to see the broad outline of B22 framed well within my FOV and suggests it too could be a viable object for another day.
Finally, with the daffodils already blooming, it was clear that winter was going to be a disappointing time for serious astrophotography, however, I was still able to attempt one final object before the winter night skies receded beyond the western horizon for another year. Surprisingly I had hitherto overlooked this object, visually located just beyond the upper edge of Barnard’s Loop, which though difficult is fortunately also strong in the Ha-wavelength. Lynds’ Dark Nebula (LDN) 1622 AKA the Bogeyman Nebula, describes the somewhat jinxed period I’ve experienced but this time fortuitously brought my earlier work together (x4 panel mosaic below: The Bogeyman – lower left + upper Barbard’s Loop + M78 – top right).
Despite my best efforts I was unable to see the Bogeyman when framing the image in APT even after stretching but fortunately it still turned out well. I noticed that most other successful images were mainlyundertaken in HaRGB, however with limited time before the clouds again inevitably rolled, the few RGB subs obtained failed to add much colour to my image on this occasion. Notwithstanding, with much greater integration time the final Ha-image holds great promise. Furthermore, the said image could be incorporated into the upper main section of the Barnard’s Loop, together with the M78 reflection nebula, to finally make a complete and worthy mosaic image consisting of six panels – see main image at the top of the page and detailed x4 panel mosaic above. Contrary to the name, on this occasion the Bogeyman completed the jigsaw and saved the day!
IMAGING DETAILS
Object
Barnard’s Loop
Constellation
Orion
Distance
1.434 light-years
Size
10o ~300 light-years
Apparent Magnitude
5
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control & Cartes du Ciel
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 camera & PHD2 guiding
Camera
ZWO1600MM-Cool mono CMOS sensor
FOV 2.65o x 2.0o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix
WATCH THIS SPACE(MAN) 